P1050: NEXT GENERATION SEQUECING CONTRIBUTES TO DEFINE PH-NEGATIVE MYELOPROLIFERATIVE NEOPLASM CLINICAL PHENOTYPE
Authors: Aldo Leone, Italia Conversano, Serafina Barbato, Giuseppina Donnarumma, Giuseppe Gaeta, Raffaella Iannotta, Francesco Muriano, Raffaella Reina, Martina Romano, Rossella Iula, Alessia Scarpa, Vincenzo Martinelli, Fabrizio Pane, Novella Pugliese
Journal: HemaSphere (2023)

Topic: 16. Myeloproliferative neoplasms - Clinical Background: In the era of Next Generation Sequencing (NGS), the molecular status of Ph- Myeloproliferative Neoplasm (MPN) patients is becoming more and more relevant for clinical and prognostic implications. Aims: We studied the performance of a 23-genes panel in defining the baseline features of MPNs and prognosis. Methods: The NGS panel was “Myeloid Solution” of Sophia Genetics v5.3.1. Our cohort included all patients who received MPN diagnosis between 2017 and 2022 in our Center, with the availability of a baseline NGS. We described the distribution of mutations in all 4 MPNs subgroups (i.e. ET, PV, pre-MF, MF) and the association of each gene with the following variables at baseline: age, splenomegaly, previous thrombotic events, CBC, LDH, circulating blasts at blood smear, peripheral CD34+ count. We explored also the association between each gene and post-ET and post-PV myelofibrosis. Results: Our cohort included 101 patients, 63 males and 38 females. The most frequent diagnosis was ET (50%), followed by PV (33%), pre-MF (9%) and PMF (8%). Median age was 57 years (range 17-79) in all groups, but PMF had a higher median age at diagnosis (70 years, range 56-82). Among the driver mutations, JAK2 V617F was the most frequent (78%), followed by CALR type I (10%), CALR type II (4%), MPL (2%) and JAK2 exon 12 (2%). 273 mutations in non-driver genes were found. Three genes (TET2, SETB1, EZH2) were mutated in more than 10% of patients, while other 3 genes (CSF3R, ASXL1 and cKIT) were mutated in more than 5% of patients. The median number of mutations per patient was 3 (range 0-7). The distribution of non-driver mutations in each subgroup can be seen in Figure 1.ASXL1 and U2AF1 mutations were more frequent in MF compared to PV (p <.001, for both genes), ET (p <.001, for both genes) and pre-MF (p 0.02 and 0.05, respectively). RUNX1 and HRAS mutations were more frequent in pre-MF compared to ET (p 0.01 and 0.02). KRAS mutations were more frequent in MF and pre-MF compared to PV (p 0.05 and p 0.04) and ET (p 0.02 and p 0.01). Moreover, MF patients harbored a higher number of mutations: the 50% of patients with MF had ≥ 4 mutations vs. 18.2% of PV, 23.5% of ET and 22.2% of pre-MF (p 0.0034). ASXL1 mutations were associated with lower Hb (p 0.01) and older age (median years 65 vs. 53, p 0,006), even if MF patients were excluded (age p 0.03 and Hb p 0.04). U2AF1 mutations were associated with post-ET and post-PV MF (p 0.01), higher LDH (median U/L 498 vs 316, p 0.01), more circulating CD34+ cells (0.25% vs 0.03%, p 0.03). RUNX1 mutations were associated with higher WBC count (median x103/mm3 12.5 vs. 8.9, p 0.02), in particular neutrophils (median x103/mm3 10.2 vs. 6.3, p 0.006), and with advanced age (median years 68 vs. 55, p 0.04). cKIT mutations were associated with splenomegaly (p 0.05) and higher LDH (median U/L 404 vs. 314, p 0.04). CEBPA was the only gene associated with thrombotic events: 25% of patients with previous thrombosis carried CEBPA mutations (p 0.02). Summary/Conclusion: Non-driver mutations were more frequent in MF patients, compared to other MPNs. ASXL1 and U2AF1 mutations were associated with MF, age and worse clinical features at baseline. RUNX1 and HRAS/KRAS mutations were more frequent in pre-MF compared to ET and could be an additional diagnostic marker. CEBPA mutations were associated with previous thrombosis. NGS panel testing is increasing in routine practice and promises to improve the accuracy and efficiency of pathological diagnosis and prognosis. Additional studies would be needed to assess the role of these genes in defining MPN phenotypes. Keywords: Myelofibrosis, Myeloproliferative disorder, Polycythemia vera, Mutation status